Some ebuilds talk about "qt" useflag. However, it has been renamed to "qt3". See: $ cd /path/to/portage/app-doc/doxygen $ fgrep elog *.ebuild | fgrep qt doxygen-1.4.2.ebuild: elog "The USE flags qt3, doc, and tetex will enable doxywizard, or" doxygen-1.4.3-r1.ebuild: elog "The USE flags qt3, doc, and tetex will enable doxywizard, or" doxygen-1.4.4.ebuild: elog "The USE flags qt3, doc, and tetex will enable doxywizard, or" doxygen-1.4.5.ebuild: elog "The USE flags qt3, doc, and tetex will enable doxywizard, or" doxygen-1.4.6.ebuild: elog "The USE flags qt3, doc, and tetex will enable doxywizard, or" doxygen-1.4.7.ebuild: elog "The USE flags qt, doc, and tetex will enable doxywizard, or" doxygen-1.5.1.ebuild: elog "The USE flags qt, doc, and tetex will enable doxywizard, or" doxygen-1.5.2.ebuild: elog "The USE flags qt, doc, and tetex will enable doxywizard, or" doxygen-1.5.3.ebuild: elog "The USE flags qt, doc, and tetex will enable doxywizard, or" doxygen-1.5.4.ebuild: elog "The USE flags qt, doc, and tetex will enable doxywizard, or" doxygen-1.5.5.ebuild: elog "The USE flags qt, doc, and tetex will enable doxywizard, or" The funny thing is that most 1.4.* ebuilds are updated to qt3 (except 1.4.7), while all 1.5.* ebuilds are not.
Fixed.